RICE and HARRISON. COPPER SENSITIVITY OF PACIFIC HERRING 



of copper-64 among particulate-bound, ionic, and 

 complexed fractions of copper recovered from the 

 bioassay water indicates that the copper was 

 primarily in the ionic form {Table 2). The mean pH 

 of the water in exposure chambers in all tests was 

 8.08 (SD = ±0.024). The mean temperature for all 

 tests was 13.3°C (SD = ±0.8°C). 



Table 2. — Percentages of copper-64 in fractions of sea water 

 recovered from the bioassay system used to expose Pacific her- 

 ring embryos and larvae to copper. 



'Total Includes copper-64 remaining in Chelex-100 resin after elution. 



Continuous Exposures to Copper 



Survival of embryos continuously exposed to 

 copper was high at all concentrations of copper 

 tested until 90 h of exposure, at which time dose- 

 related mortalities occurred (Figure 3). The period 

 during continuous exposure when embryo deaths 

 begin is termed the reaction period. Mortalities of 

 developing embryos at copper concentrations of 35 

 /ug/l and higher were significantly different from 

 controls (P<0.01). Virtually no hatching occurred 



at concentrations above 45/Ltg/l copper. Develop- 

 mental features observed in the control embryos 

 during the onset of the reaction period included 

 the appearance of eye pigmentation, the onset of 

 coordinated body movements, and the initiation of 

 heart beat. Embryos continuously exposed to cop- 

 per concentrations of 100 /i.g/1 copper and higher 

 developed an opaque cast to the chorion, which 

 was followed later by whitish discoloration of the 

 body. Embryos continuously exposed to 200 /u.g/1 

 copper developed an opaque change in the chorion 

 at 60-72 h from fertilization, with body discolora- 

 tion, spasmodic contractions, quiverings, and re- 

 duced fin fold development occurring at 84-96 h 

 from fertilization. 



Herring larvae continuously exposed to copper 

 were many times less sensitive to copper than 

 herring embryos. Larval mortalities differed sig- 

 nificantly from controls at concentrations of 300 

 /Ltg/l copper and higher (P<0.05) (Figure 4). Prior 

 to death the larvae sank to the bottom of the expo- 

 sure chamber and patches of whitish discoloration 

 were observed over the bodies. Spasmodic quiver- 

 ing and whole body contractions were observed in 

 larvae at concentrations of 1,400 /xg/1 copper and 

 above. 



The toxicity curves for continuously exposed 

 herring embryos and larvae are shown in Figure 5. 

 Median lethal times for each copper concentration 

 tested and 95% confidence limits are detailed in 

 Table 1. 



100 



Figure 3. — Percent cumulative mor- 

 tality of Pacific herring embryos con- 

 tinuously exposed to copper (micro- 

 grams per liter). Mortality curves 

 shown are the fitted logit curves used to 

 establish median lethal times. 



+-> 

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Z3 



-H Hatching 

 20 40 60 80 100 120 140 160 180 



Hours from fertilization 



351 



